When working the soil with a vehicle adapted to be used in agriculture and having a working implement attachment, the problem arises of performing the work to be accomplished at an optimum efficiency. U.S. Pat. No. 3,686,935 to May shows a method and apparatus for monitoring the performance of a draft vehicle for agricultural use. The draft vehicle has a fuel injection engine, driving wheels, a transmission connecting the engine to the wheels, a torque converter, and measuring elements to measure the circumferential speed of the driving wheels, the speed of the vehicle, the speed of the engine, the rate of fuel supply to the engine, the torque supplied to the converter, and the torque supplied by the converter. The vehicle parameters, including vehicle speed and torque, are processed into electrical signals relating to vehicle performance and efficiency for display within the view of the vehicle operator. It would be advantageous to obtain some indication of efficiency without the need to measure ground speed and torque directly. The system taught by the May patent is for use with a vehicle having a torque converter and directly measures engine and converter torque.
U.S. Pat. No. 3,998,094 issued to Martin shows a method of and apparatus for measuring the distance traveled per amount of fuel consumed by a vehicle. Pulses are applied to a fuel injection nozzle and to an oscillator drive and trigger circuit. Oscillator drive and trigger circuit generates a pulse repetition frequency signal and a pulse length signal. These two signals are fed to a computer, which generates a fuel flow rate signal which is applied to a divider and to an integrator. Vehicle road speed signals are applied to the divider. The divider divides the vehicle road speed by the fuel flow rate, and generates a signal indicative of distance traveled per amount of fuel consumed. This electronic system processes speed and fuel consumption information into a signal which is proportional to the distance traveled per unit of fuel consumed. However, the apparatus does not give an indication of efficiency for the operator of the vehicle to use.
U.S. Pat. No. 4,113,046 issued to Arpino includes a position sensor which generates a signal proportional to the position of the accelerator pedal. This signal is amplified and differentiated so that a signal whose magnitude is proportional to the rate of change of the position of the throttle is generated. Similarly, a velocity transducer generates a signal which is proportional to vehicle speed. This signal is amplified and differentiated into a signal whose magnitude is proportional to the rate of change of the vehicle speed. These two signals are applied to a differential amplifier whose output drives the meter. The output of the differential amplifier is an efficiency signal whose magnitude is proportional to the difference between the amplitudes of the throttle rate signal and the acceleration signal. The meter indicates whether or not the vehicle is accelerating efficiently. Clearly, it would be advantageous to have a meter which indicates efficiency not only during acceleration but also during steady state operation so that a vehicle operator can make appropriate throttle and gear shift adjustments.
U.S. Pat. No. 4,157,030 issued to Keely includes a system for deriving the fuel consumption of a vehicle. The system includes a vehicle speed transducer and a control unit coupled to a fuel injector to produce pulses proportionate to the rate of fuel flow. The vehicle speed and fuel flow signals are combined with the signal indicative of the number of gallons remaining to produce a signal which relates to how much further the vehicle can travel before the fuel supply is exhausted. Again, such an apparatus does not provide a measure of efficiency which can be used by the vehicle driver to adjust the throttle or gear position of the vehicle.
U.S. Pat. No. 3,006,144 issued to Arnett et al, teaches a fuel control apparatus responsive to approaching engine instability. The object of the apparatus is to modulate the fuel supply to the engine whenever the engine approaches its unstable range of operation. A speed tachometer generates a signal which is proportional to engine speed. Similarly, a fuel flow meter generates a signal which is proportional to the fuel flow to the engine. These signals are compared to provide the control of a fuel valve. Thus, signals corresponding to engine speed and fuel flow are used to make adjustments in the rate of fuel flow in accordance with the known characteristics of a particular engine when the system is properly adjusted. Again, there is not taught an engine efficiency meter which can provide an indication for the operator to adjust the vehicle throttle or gear shift to improve efficiency. These are some of the problems this invention overcomes.